The design of a kind all-purpose power supply is introduced. This method is to drive the power MOSFET switch to carry on the DC/DC transformation by using the pulse-width Modulation signal produced by the special-purpose chip TL494. The adjustable function is carried on by changing the reference voltage of the internal integrated operational amplifier in TL494. This design describes not only the module type structure of the power but also explains its relevant control circuits and protection circuit. Then, it also can test the power and get the relevant waveshape.